Advantages and disadvantages
The wheel motor has certain advantages and disadvantages that must be considered. In this case, it is worth considering the variety of this element.
The main advantages are the following:
- High efficiency factor. The above information indicates that the efficiency is at least 90%. This value is not typical of many electric motors.
- The design is characterized by simplicity and reliability. The absence of wear parts determines a long service life.
- The device is capable of providing a high speed of movement of transport. Common versions with a power of 500 watts are capable of speeds of about 45 km / h.
There are also several significant disadvantages. They are as follows:
- Low torque. The electric motor of the second type is characterized by a higher torque.
- Quite large in size. This does not allow the use of a wheel motor when creating compact and efficient designs.
- Great weight. When compared with other motors, the considered one has significant weight.
Principle of operation
A common motor-wheel is practically no different from a brushless synchronous motor.
Its features are as follows:
- A rotating magnetic field, which is a moving force, is created by the motor by switching the winding with a special key by the controller.
- Here the speed of rotation of the wheel also depends on the indicator of the switching frequency.
- A fairly large number of permanent magnets are used when creating a structure.
- The design has no brushes and other rubbing parts, except for the bearing on the axle. Due to this, the efficiency indicator increases to 90% and the degree of structural wear is reduced.
Direct drive wheel motor
A direct drive wheel motor is characterized by two main elements: stator and rotor.
Their features are the following:
- The rotor is represented by a winding wheel axle. It attaches to the bike frame.
- The stator resembles bushings with a powerful permanent magnet. The spokes and the rim are attached to it, during movement it rotates around the axis.
- The design under consideration is quite simple and reliable, since there are no rubbing elements.
- The advantage is that the power can reach 5000 watts. In addition, the maximum travel speed is 100 km / h.
- The efficiency indicator is much higher when compared to a gearbox.
However, there are several significant disadvantages in a direct drive mechanism, for example, friction occurs at the moment of movement. Therefore, pedaling will become much harder. In addition, to achieve the required power level, a device with large dimensions is needed.
In order to be able to ride against the wind, when choosing, you should give preference to electric bicycles. In addition, the installed electric motor allows you to cover a long distance at a significant speed with less cost.
The wheel motor was invented almost simultaneously with the electric motor. It is characterized by its own characteristics, in which we will talk in more detail below.
How to choose a wheel motor for a bike. tips
The main characteristics of the wheel motor determine the selection recommendations.
They look like this:
- Achieving speeds in excess of 30 km / h requires a direct drive mechanism with a power of 500 watts or more. However, when installing it, it should be borne in mind that when the motor is turned off, pedaling will be much more difficult.
- If a speed of about 30 km / h is sufficient, then you can give preference to a motor-wheel with a gearbox, the power of which is 350 W. Due to this mechanism, conditions are provided for a confident ascent uphill, and when driving with the engine off, additional resistance will not be created. Also, the mechanism is small in size and weight.
Types of motor wheels
There are two different motor-wheels, which can be used to create bicycles and a second transport.
Motor-wheel for a bicycle. description
The key feature of the wheel motor is that the wheel serves as the stator axis of the electric motor. The emergence of modern injection molded batteries has become an impetus for the development of this area, since they can withstand a large number of recharge cycles.
The main operational characteristics determine the use of a motor-wheel in the creation of bicycles and mopeds, as well as a second light transport. At the same time, the device has its advantages and disadvantages.
Its power ranges from 250 to 350 W.
The key features of this device are as follows:
- The gearbox is designed to increase the torque, which becomes a prerequisite for reducing the travel speed to about 30 km / h. However, due to this, climbing uphill is greatly simplified, less effort is required. Achieve similar torque with direct drive is possible only with an increase in power to 1500 W.
- The design of the gearbox is represented by a combination of several gears. The service life of moving parts largely depends on the mode of operation and correct maintenance.
- During operation, gears become a prerequisite for the occurrence of noise or hum. In addition, due to the resulting friction, the structure can become very hot.
- The main distinguishing features are small weight and compactness. Modern technologies make it possible to make a device whose diameter is larger than the diameter of the sleeve.
- The negative side is that the maximum power is about 500 watts.
Features of the installation of motor wheels
Having chosen a suitable motor, you can proceed to the direct installation procedure. It can be done by hand.
The instruction looks like this:
- To begin with, unscrew the nuts, which secure the wheel, after which it is removed.
- The motor-wheel is being installed in the vacant space.
- After the assembly of the entire circuit is carried out, but the fasteners are only cashing in. This is done in order to check the performance of the device and the tent, the trajectory of the wires.
Analysis of different electrical sets
There are two possible options for electric bike kits:
- Motor Installed in the wheel. This system does not take advantage of the cycling gear system.
- A motor inserted in a carriage (such as in the Optibike MBB systems) that can be rotated in parallel with your feet. This system is activated through the bicycle chain drive.
In the first case, the chain transmission system remains unused, and you can not rely on the maximum engine efficiency when going uphill. In the second case, of course, you will lose a little on friction in the chain drive, but you can optimize the efficiency of the engine when changing the speed.
When changing gear, torque is always lost. Therefore, it is advisable to always start climbing the mountain in the appropriate gear or do as little shifting as possible when climbing.
Even a geared motor is affected by gear changes. After the rider changes gear, any engine will have to change the speed. In this case, it will be better if the cyclist gives extra push through the pedals after shifting.
The front motor wheel also loses torque along with the rider when changing speed, as they are combined into the same gear system.
Electric motors specialization
The Electric Bicycle Wheel Motor can be specially designed for better uphill climbing or optimized for increased range or increased travel speed. High horsepower engines have a high hill climbing ability (torque), but they reduce the travel range (drain the battery quickly).
The power efficiency of a motor is NOT constant, it has a maximum value at a certain speed. Also, its value depends on whether the speed increases or decreases.
Ordinary motorized or geared?
It doesn’t matter if the electric motor is connected via a chain drive (drives to the carriage) or not (front, rear motor, friction gears), the bicycle speed system will still be involved.
The gear motor wheel allows you to move with the introduction of a reduction in the gear ratio. It can help a cyclist to climb a very steep hill when using a motor with a highly reduction planetary gear. In this case, the engine will operate close to the highest efficiency point, as it will maintain high rpm. But still, there will be a loss of efficiency in a motor with a gearbox, since such systems are complex and some frictional waste is inevitable in them.
Gearless systems DO NOT reduce engine speed. Consequently, the efficiency of the engine in them is not constant, but very often depends on the speed of the bike. But such systems are simple, therefore their total efficiency is higher in comparison with geared motors.
As you can see, there is a problem of choosing between an electric motor with a gearbox and without it. On the one hand, the former can maintain the same efficiency of the motor over a wide range of speeds, while the latter have inevitable losses when the speed decreases. On the other hand, electric motors without a gearbox have high overall efficiency.
However, it is safe to say that in other riding conditions a motor without an undershift will do its job better (especially on frequent long trips) than overly complex systems with a gearbox.
After each ascent, there is a descent from the hill. it’s just like the cycle of substances in nature. On the downhill, with regenerative braking, the electric motor can charge the battery and extend the range of the e-bike. Electric motor designed by V.V. Shkondina can, during generation, return the maximum part of the energy that was spent on climbing the mountain.
Generating energy slows the bike down, so installing a Shkondin motor would be a good idea if you want to limit the bike’s top speed downhill, naturally without using the brakes.
In addition to regenerative resistance, each electric motor has internal friction, so any drive on an electric bike to some extent Decreases the top speed with NAC compared to a conventional bike.
What is a bicycle wheel motor and how to choose it
Many people choose to use electric bicycles, because they help to ride against the headwind and climb the High Hill. Everyone can now assemble an electric bike with their own hands, thanks to the many sets brought from China.
But the electric bicycle only increases the strength of a person, and does not completely replace it. Thus, you will still need to pedal when riding an e-bike, and this is especially necessary when driving up a slope.
Unlike the second motorized vehicle, which has only a motor to push the car forward, an electric bicycle combines the power of a motor with the power of the rider. Machines that combine power from different sources (for example, an engine and a person) are called hybrid.
When a person is not sure that a specific set with an electric motor will help climb to the top of a hill, he is lost in thought: what if the hill will be even steeper or longer. And naturally, everyone wants the most powerful electric bike kit. However, in many cases, the most powerful electric motor will be overkill, and you will end up spending too much money and carrying around much more weight than you really need.
You can climb a low hill with almost any wheel motor for a bicycle. And if you press the pedals lightly, you can easily climb a steep hill, even under difficult conditions. strong headwinds and heavy riders’ weight. In comparison with conventional bicycles, electric bikes will pleasantly surprise you.
Examples from real life situations
Take for the first example a standard motor with a maximum power of 250 watts at 10 km / h and a cyclist who can also bring in 250 watts (not trying hard) to maintain a given speed. Together they deliver one impressive 500W of power.
- At a speed of 10 km / h, a rider can climb a hill with a slope of 17.5% with 500 watts of combined power.
- At a speed of 8 km / h, a cyclist can climb a hill with a 17.5% incline with his 250W and running at 80% with a 200W motor.
- At 6 km / h, a cyclist can climb a hill with the same 17.5% bow with his 250W and 60% 125W motor.
At first glance, these results may seem completely inaccurate, because only the efficiency of the electric motor is decreasing along with the speed, and it seems that the cyclist can still climb the same steep slope.
This inaccuracy will be resolved when we understand how important a person is to the operation of an e-bike. Let’s see what would happen if the cyclist did NOT press the pedals at all and all 500 watts (as in the example above) came from the motor.
- At 10 km / h, a cyclist would only be able to climb a 17.5% incline with the 500 W engine running at 100%.
- At a speed of 8 km / h, a rider can climb a hill with a lower incline of 17% with a 400 W motor running at 80%.
- At 6 km / h, the rider can drive up a hill with a slope of 14.5% with only 50% of the 250 W motor.
These results are taken from the e-bike calculator with the following inputs: Total weight. 100 kg; frontal resistance area. 0.4 kV meters; friction coefficient. 0.7; lifting length. 100 m; headwind speed. 10 km / h and rolling resistance coefficient. 0.007.
Race around the city on a self-assembled electric bike with a motor wheel:
Cyclist Strength is most important when you need to maintain the speed on an e-bike, because when it drops, the engine efficiency is greatly reduced. By analyzing this, you will be able to understand how an e-bike is different from any other motorized transport and why installing geared motors is not always the best choice. It is better not to put a motor with a gearbox in the front wheel at all, because it should have a free roll.
Electric motor for bicycles: MAIN TYPES of electric motors and WHAT THEY DIFFERENCE
An ideal solution for those who want to make an electric bike with their own hands is an electric motor for a bicycle. Consider the main types of electric motors, installed on a regular bike, you get an electric bike. Able to reach a speed of 50-70km / hour.
The wheel motor is the most common type of electric motor today. It should be noted that this type of electric motor is usually installed when converting a regular city bike into a bicycle with an electric motor.
As for the appearance and design of the bike, they hardly change, since the motor-wheel is almost invisible. This engine is mounted to both the front and rear hubs, but sometimes it happens that they put one motor on each wheel.
The bike is considered to be completely re-equipped when the battery and throttle are installed. Often the wheel motor is sold with spokes that are already mounted to the hub.
The motor-wheels have a power in the range of 150. 2000 W. Note also that motor wheels have three main versions: 24, 36 and 48 V. And each of these types requires its own battery.
A bicycle on which a motor-wheel is installed is capable of accelerating to 60-70 km / h and has a power reserve of about 40-50 km. Naturally, if you move uphill, these indicators are significantly reduced.
To increase the power and speed of the electric bike, some experimenters increase the power supply up to 72 V. But, this is quite a risky idea, because the electric motor installed on the bike can be damaged.
SINGLE CYLINDER TWO-STROKE TYPE MOTOR (DISPENSING VOLUME 48 cm3) FOR road bikes
The installation of such a motor is carried out to the bike frame, and the rotational movement is transmitted to the front sprocket. This enables full use of the speed switches.
The working fluid of this engine is a gasoline-oil mixture. The engine is cooled by air and has a power of 1.5 HP, and this is enough to drive on the road without hills.
When climbing or accelerating, the cyclist should assist the engine with the pedals. The engine speed limit is 30 km / h. The engine “eats up” 1 liter of fuel per 100 km.
Naturally, the engine comes complete with a gas tank and muffler to complete your bike-to-moped conversion.
The outboard is a standalone unit attached to the bottom bracket or bottom tube of the bike. A mandatory point is that a special protective cover is installed on the electric motor and chain drive.
The engine transmits power to the rear sprocket via a chain drive. The engine is powered by a battery that is attached to the bottom of the bike’s supporting platform.
The power consumption and speed of the bike is regulated by a special electronic controller. The controller is controlled by the steering wheel handle (by analogy with the throttle handle in a motorcycle).
If we compare this design with a motor-wheel, then the total mass of the bicycle will increase slightly. However, the speed of the electric bike will increase significantly, and can even reach 120 km / h.
As well as the motor-wheel, the electric drive of the considered types can be installed on almost any bicycle.
Electric motor for bicycles: MAIN TYPES
In this article, we will look at the main types of such a device as an electric motor for a bicycle. So, it’s worth saying that the motors that are installed on electric bicycles are of the following types:
- Wheel motor;
- Outboard engine;
- Engine in friction gear.
MOTO KIT for bicycles
Today, a motorcycle kit for a bicycle is not uncommon. There are a number of different bike-mounted motors on sale. Usually, a motorcycle kit provides universal mounts, which fit most modern bikes, but there are motors designed only for certain bike models.
Some models of motorcycle kits that are most popular, consider further:
ENGINE WITH FRICTION GEAR
The electric drive, which is based on a friction mechanism, works thanks to the following principle. The transmission of torque from the shaft of the electric motor is carried out directly to the tire of the vehicle wheel.
This type of transmission of torque from the engine to the wheel is considered ineffective, since it has a number of quite significant disadvantages, namely:
- Very low efficiency;
- Significantly reduces wheel life;
- Requires constant monitoring of the pressure in the wheel;
- In wet weather, the transfer roller slips noticeably.
The only thing that justifies the admissibility of using an electric motor of this type is that it can be simply an institution without disassembling the bike.
MOTORETS FOR BIKE “COMET” of suspended TYPE
This motorcycle kit is attached to the trunk of the rear wheel floor. Rotational motion from the engine is transmitted to the rear wheel of the bike. Sometimes the motorcycle kit is installed on the front wheel floor of the bike. For this case, engine power is transferred to the front wheel.
The motorcycle kit is presented in several modifications: the engine displacement ranges from 1 to 2 hp. It should be noted that the maximum speed of the most powerful engine is 50 km / h.
The motorcycle kit in question has a built-in muffler and a fuel tank, the ability to quickly dismantle the engine, and a fairly low weight (about 5 kg).
This is one of the positive qualities, however, there are also negative points, and quite significant: the motorcycle kit has a fairly high cost, the quality of the drive device raises many questions, the aesthetic component of the engine is far from perfect (as if they had somehow installed the motor from a lawn mower with their own hands).
Bicycle MOTOR YAMAHA
Even bicycle motors are produced by a well-known manufacturer. It is worth noting that these engines have much better technical and quality characteristics than the moto kits mentioned earlier. These motors can have up to 4 HP, which is enough to not help the pedals.
But the cost of such a toy is quite impressive. Today Yamaha is gradually switching to the manufacture of bicycle electric motors, and in the near future gasoline engines from this manufacturer will be in short supply (there are already few of them).